BiologyClick for a model sheet diagram of Plorgonarian internal organs, because that's apparently a thing that exists.

Plorgonarians lack an internal or external skeleton. They are tripeds, walking on three stout legs with two toes on each foot. Their body is thin and they are slightly shorter than an average human. They have two long thin arms and three elongated fingers on each hand.
Their head sports a large single eye that is bigger than their brains, a wide mouth with two purple tongues, and a short antenna on the top of their head called a plorgonarian quart flanch. The quart flanch is capable of reading several strata of subspace ether transmissions, giving the plorgonarians advanced senses of hearing and smelling, and making them immune to loud noises and magic conveyed via sound. The antenna can go orange when they age, similar to men going bald- which is to say, it doesn't happen to all of them, and it can happen to some prematurely. Plorgonarians are known to appreciate certain odors which humans and other alien species consider noxious or horrible.
Female plorgonarians grow hair of various colors and style it, much like humans style their own hair. Some male plorgonarians grow hair as well, but theirs is much sparser. Plorgonarians are incapable of growing body hair.
Internally, plorgonarians have two hearts and small brains. Their blood is a strange marbled mix of green and purple. Their eyes are so large that they are visible on the roof of their mouths as a bulge, similar to the eyes of amphibians such as frogs. They are capable of unhinging their jaws (the jaws themselves are made of cartilage).
Both male and female plorgonarians have prominent Adam's apples.
Headcanon Zone
Plorgonarians reproduce like frogs, but with direct development. That is to say, there's no tadpole stage, eggs just hatch into small versions of the adult form. Direct development is rare in species on Plorgonar.
On average, each clutch will produce somewhere between two to six children. Only children are possible, but rare. Pleakley was part of a two-child clutch with his brother Bertley, and then their sister Pixley was part of a one-child clutch a few years later.
Eggs resemble frog eggs, a semi-transparent gel-like globule with a black dot in the middle. This also causes them to resemble plorgonarian eyes.
Rather than blood, Plorgonarians have hemolymph.
Plorgonarians produce large amounts of the aldehydes heptanal, octanal, and nonanal. CulturePlorgonarians are a space-faring civilization. The shape of a plorgonarian's head is seen as a culturally important symbol. Not only is it the head shape of the dominant species, their planet is also shaped like a plorgonarian head. Houses are designed to look like plorgonarian heads as well.
The specific culture Pleakley is from resembles modern Earth culture- nuclear families, kids going to school, etc. There are many differences of course, but it's very similar despite being aliens.
One of the differences is the fact that this society does not use currency, instead operating off of a "take what you need, and give what you can" philosophy. When interacting with other cultures that use money, plorgonarians can adjust to the idea of physical money as an extension of trading, but things like bank accounts and credit or debit cards are incredibly confusing to them. If the money isn't physically there as trading material, they'll just assume things are free. Wendy Pleakley is currently in major debt on Earth due to this.
Being unmarried as an adult is looked down upon. While plorgonarians can marry for love, it's not uncommon for parents to arrange marriages for their children if those children are unmarried by their thirties.
Clothing worn often emphasizes the shoulders.
PlanetPlorgonar, while colloquially referred to as a planet, is actually a moon!
The atmosphere on Plorgonar is thin, resulting in a sky that always looks like nighttime. Clouds are common, and appear bright pink when viewed from space.
There is no snow or mud on Plorgonar.